This invention relates to an apparatus for handling tubular goods such as pipe, casing, collars, etc. and for transferring such tubular goods between a drilling rig and a pipe rack. It relates more particularly to a pipe handling apparatus which can be easily disassembled, transported between drilling rig sites and reassembled at the new site.
In the prior art there are various methods and devices for lifting and moving pipe to and from pipe racks and an elevated drilling rig floor. One of such methods simply attaches a wire cable to the pipe and then the cable is lifted by a hydraulic winch which is typically mounted on a truck parked near the rig. Cranes and hydraulic driven chains have also been used to lift and move the pipe. As these heavy lengths of pipe impact against the different chain-driven mechanisms, the chains were caused to "jump" or tear the sprockets or the chain. Pipe transferred by these methods can be dropped on personnel or equipment below causing severe injury and damage inasmuch as the pipe can weigh thousands of pounds and often must be lifted to heights of forty feet or more. Additionally, if the pipe is dropped or banged against other structure, or even if it contacts the device in accordance with its operating mode, the threaded ends can be damaged or the pipe bent.
Inclined troughs for the transfer of pipe have also been used wherein the pipe is frictionally slid along the trough surface. This action often causes excessive wear on pipe especially the threaded ends which must be protected from such wear. It was thus often necessary to keep the metal thread protector on as the pipe was moved along the trough for removal when the pipe was on the drilling rig platform. This necessary care of the threads and pipe ends creates an extra step in the installation of the pipe or other tubular in the hole resulting in a longer cycle time.
The prior devices, especially when designed for onshore operations, should be easily disassembled, moved to the flatbed of a truck positioned nearby, driven to another drilling rig site, unloaded from the truck to the proper position and reassembled. In the past this operation has been complicated and time-consuming. Frequently the truck cannot be positioned parallel to the catwalk because the pipe racks are in the way or because of other site logistic problems. Thus the truck must be parked parallel to one end of the catwalk. Additional cranes had to be supplied to lift and position the heavy, cumbersome devices. The devices had protruding portions which had to be completely disassembled and reassembled at the new site. In some instances these problems proved to be too burdensome and the devices were just left at the drilling rig site for the entire drilling cycle requiring separate individual devices for each site.